RxNs

Scheme 1 Aza-Michael reaction of p-anisidine in different solvent systems. Scheme 2 Michael reaction of indole in different solvent systems.
Scheme 3 Reaction between 4-nitrobenzaldehyde and 2-methylindole in different solvent systems and under catalyst-free conditions.

Source: Gu,Y. and Jérôme, F. Glycerol as a Sustainable Solvent for Green Chemistry Green Chemistry [Online] 2010, 12, 1127-1138